Recently devices using heat energy obtained by collecting solar light as clean energy that does not affect an environment have been introduced. As such devices, solar heat power generation devices performing power generation by converting the heat energy obtained by collecting the solar light into electric energy have been developed (e.g., see Patent Document 1).
In the solar heat power generation devices described above, light and heat are typically collected by a combination of a light collecting unit using a mirror and a solar heat receiver. Such a combination system of the light collecting unit and the heat receiver generally includes two types of systems called a trough light collecting system and a tower light collecting system.
The trough light collecting system refers to a system for causing solar light to be reflected by a semicylindrical mirror (trough), collecting the solar light and its heat on a tube passing through the center of the cylinder, and heating a heat medium flowing in the tube. However, in the trough light collecting system, since the mirror changes its direction to track the solar light under uniaxial control, it cannot expect the heat medium to be heated to a high temperature.
In contrast, the tower light collecting system refers to a system for disposing the solar heat receiver on a part of a tower erected from the ground, arranging a plurality of reflected light control mirrors, each of which is used for light collection and is called a heliostat, so as to surround the part of the tower, guiding the solar light reflected by the heliostats to the solar heat receiver, and thereby collecting the solar light and its heat. In recent years, from the viewpoint of achieving much higher efficiency of a power generation cycle, the solar heat power generation devices based on the tower light collecting system for allowing the heat medium heat-exchanged by the solar heat receiver to be heated to a higher temperature have been actively developed.
The solar heat receiver used in the tower light collecting system, as disclosed in, for instance, Patent Document 2, is equipped with a casing having an aperture through which solar light enters, and a piping system that is provided in the casing and discharges a heat medium, which is sent from an external fluid supply source, to an external fluid supply destination after the heat medium is heated by the solar light. The piping system includes: a plurality of heat receiver tubes that are housed in the casing and receive the solar light, which enters through the aperture of the casing, to heat the heat medium flowing inside the heat receiver tubes; an inlet header tube that is connected to one end side of each of the heat receiver tubes and distributes the heat medium, which is introduced from the fluid supply source, to each of the heat receiver tubes; and an outlet header tube that is connected to the other end side of each of the heat receiver tubes, collects the heat medium passing through each of the heat receiver tubes, and leads the heat medium to the fluid supply destination.